| rpms at 850 range with adv. timing 16 tdc/ 700 at 10 degrees [message #264860] |
Sun, 26 October 2014 15:13  |
budworks521
Messages: 137
Registered: October 2013
Location: Grand Rapids MI 1974 Pain...
Karma: 4
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I finally bought a tach meter and started off with my distributor slightly advanced to 15/16 tdc. My vac gauge reads a steady 18 inches for quite awhile. My best readings on the vac gauge was with the timing advanced at start up. I decided to check rpms and they were in the 837/857 range. I then moved the distributor closer to 10/12 degrees tdc and my rpms decreased to 710 ranges. My two idle screws didn't make much of a difference when opened a 1/4 turn. The engine runs fine for awhile and then slowly fades 2/3 inches. It isn't stalling anymore but my choke seems to take quite some time to fully open. If I throttle the engine it drops 2-4 inches and then shoots to 25 or so then a slight drop to 15/14 and wavers back and forth. I was wondering if running the engine without a full 90 degrees on the choke would cause these symptoms and a if the symptoms are more in line with a restricted muffler. I see carbon sooty deposits on outside of muffler. Though the exhaust pushes fine at tailpipe. Steady drum. I plan on buying an electric choke soon but was wondering if a bad muffler would cause a great reading on the vac gauge to start and then the gauge acts differently as the engine runs (back pressure and lower readings)??? Any and all comments from previous experiences with this vac reading scenario would be great. Thanks gentlemen..
1974 Painted Desert
455 upper half rebuild
constant project inexperienced mechanic
Grand Rapids Mi
Always trying to learn
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| Re: [GMCnet] rpms at 850 range with adv. timing 16 tdc/ 700 at 10 degrees [message #264867 is a reply to message #264860] |
Sun, 26 October 2014 18:29  |
james Ernst
Messages: 79
Registered: December 2013
Location: Lincoln, NE
Karma: -4
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Lawrence,
The vacuum break or pull off was shot on mine and wouldn't pull the plate
at all. So I replaced that and went ahead put in an electric choke. It
works great now.
Jim Ernst
77 Palm Beach
77 Kingsley
Columbus, NE
On Oct 26, 2014 2:14 PM, "Lawrence Harrison" wrote:
> I finally bought a tach meter and started off with my distributor slightly
> advanced to 15/16 tdc. My vac gauge reads a steady 18 inches for quite
> awhile. My best readings on the vac gauge was with the timing advanced at
> start up. I decided to check rpms and they were in the 837/857 range. I then
> moved the distributor closer to 10/12 degrees tdc and my rpms decreased to
> 710 ranges. My two idle screws didn't make much of a difference when opened
> a 1/4 turn. The engine runs fine for awhile and then slowly fades 2/3
> inches. It isn't stalling anymore but my choke seems to take quite some
> time to
> fully open. If I throttle the engine it drops 2-4 inches and then shoots
> to 25 or so then a slight drop to 15/14 and wavers back and forth. I was
> wondering if running the engine without a full 90 degrees on the choke
> would cause these symptoms and a if the symptoms are more in line with a
> restricted muffler. I see carbon sooty deposits on outside of muffler.
> Though the exhaust pushes fine at tailpipe. Steady drum. I plan on buying an
> electric choke soon but was wondering if a bad muffler would cause a great
> reading on the vac gauge to start and then the gauge acts differently as
> the engine runs (back pressure and lower readings)??? Any and all comments
> from previous experiences with this vac reading scenario would be great.
> Thanks gentlemen..
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
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Jimbalaya
No Coach yet
60 Olds 88
66 Toro
76 Toro
86 cutlass Supreme
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| Re: [GMCnet] rpms at 850 range with adv. timing 16 tdc/ 700 at 10 degrees [message #265148 is a reply to message #264867] |
Thu, 30 October 2014 18:42 |
Otterwan
Messages: 946
Registered: July 2013
Location: Lynnwood (north of Seattl...
Karma: 0
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Senior Member |
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james Ernst wrote on Sun, 26 October 2014 16:29Lawrence,
The vacuum break or pull off was shot on mine and wouldn't pull the plate
at all. So I replaced that and went ahead put in an electric choke. It
works great now.
Jim Ernst
77 Palm Beach
77 Kingsley
Columbus, NE
Choke pull off only works immediately after starting, to pull the choke open just a bit to prevent stalling. After that the thermostatic spring takes over. If your choke is taking a long time to open, it sounds like you have a leak in your hot air tubing somewhere. Check all the connections. Spraying Gumout or some other carb cleaner around the joints will help you find leaks.
1977 Birchaven, Lynnwood WA - "We may not be able to stop all evil in the world, but I know that how we treat one another is entirely up to us."
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